Hybrid end-capped reactive silicone polymers

ABSTRACT

The present invention provides novel “hybrid” silyl-terminated polymers that contain at least two different reactive end-capping groups. The “hybrid” silyl-terminated polymers of the present invention are produced by a novel single multi-step end-capping reaction of at least one silanol-terminated polymer with at least two silanes in the presence of a catalyst.

FIELD OF THE INVENTION

[0001] The present invention relates to the preparation of “hybrid”silyl-terminated polymer backbones and compositions produced therefrom.More particularly, the present invention relates to “hybrid”silyl-terminated polymer backbones having two different reactiveend-capped groups produced by reacting at least two different silaneswith at least one silanol-terminated polymer backbone in a singleend-capping reaction process.

BRIEF DESCRIPTION OF RELATED TECHNOLOGY

[0002] Silicone based polymers are widely used in adhesives andsealants. These polymers are widely used in various industries includingthe construction, automotive, electronic and consumer industries. Thecured silicone elastomers are noted for their flexibility and stability.Many RTV silicones used today are based on polydimethylsiloxanebackbones and are formed from the condensation reaction between asilanol-terminated polyorganosiloxane and a silane end-capper.Conventional silicone end-capping technology typically involves reactinga single silane end-capper with one or more silanol-terminatedorganosiloxane groups, which results in reactive silicones havingidentical terminal end groups. Silane end-cappers can be chosen so thatthe capped silicone polymer can cure by more than one curing mechanismand/or the rate of curing can be controlled. Such compositions areexemplified in Loctite's U.S. Pat. Nos. 5,300,608 and 5,663,269.

[0003] Reactive silicone polymers having different end-capping groups oneach end of the same backbone, have heretofore not been known. Differentsilanes, having different rates in cappping the silanol-terminatedpolyorganosiloxanes, have hampered the ability to obtain hybridend-capped reaction products. Instead, physical mixtures or blends ofdifferent reactive silicone polymers have been used to take advantage ofthe different functionalities on their respective end-capping groups.Such physical blending, however, has offered limited usefulness due totheir disappointing physical properties and performance properties,including such properties as curing speed, gas and oil resistance, andelongation, tensile strength and shear strength. To improve theseproperties, additives may be incorporated, but require additional costand processing and still may not produce satisfactory results.Furthermore, some physical mixtures are “extra” active under certainconditions and thus, may require special measures to ensure acceptableshelf-life.

[0004] Accordingly, there is a need for “hybrid” end-capped polymers andcompositions and for processes for producing same. Moreover, it would bedesirable to be able to produce silyl-terminated polymers havingdifferent reactive groups on each end, each of which have differentreactive functionality.

SUMMARY OF THE INVENTION

[0005] Whereas conventional means for end-capping silanol-terminatedbackbones produced identical or uniformed end-capped groups, for examplea methacryloxypropyldimethoxy group on each terminus of the polymerbackbone, the present invention provides for more than one type ofend-capping group to be present on the same backbone, each of which havedifferent functional groups present. The “hybrid” end-cappedsilanol-terminated polymer compositions of the present invention areproduced by a single end-capping reaction process, which includescombining at least one silanol-terminated polymer backbone, with atleast two different silanes, desirably in the presence of a catalyst.The resultant reaction product is a reactive silyl-terminated polymerhaving different end-capped groups on its terminal ends. The term“hybrid” is meant to include at least two different reactive silylend-capping groups on a polymer backbone. The different end-cappinggroups may have one or more different functional groups directly orindirectly bonded to their terminal silicon atoms. Desirably, an alkoxygroup, in addition to other functional groups, is present on each of thesilyl end-capped polymers.

[0006] The inventive methods provide novel silicone compositions thatovercome the disadvantages of conventional physical blends ofpolysiloxanes heretofore enumerated. The resultant “hybrid” compositionsof the present invention have improved properties and performance whencured over the conventional physical mixtures of polymers. Among theseimprovements are included better elongation and faster cure thancomparable physical blends of “hybrid” silicone compositions.Additionally, subsequent to cure, the inventive compositions haveexcellent resistance to oil and radiator coolant fluids as compared toconventional physical blends of different end-capped polymers. Further,the inventive compositions have long shelf-life stability without theneed for addition of special stabilizing agents.

[0007] Thus, the present invention provides for excellent hybridend-capped polymer compositions that are extremely useful in manysilicone applications, especially in adhesive applications requiring afast room temperature vulcanization (RTV) curing product. The inventive“hybrid” polymers and compositions based thereon can be tailored tospecific uses by the choice of terminal end-capping combinations,thereby imparting specific properties to the final compositions.

[0008] In one aspect of the invention there is provided a method forpreparing a silyl-terminated polymer, and desirably an alkoxysilyl-terminated polymer, having a different end-capping group at eachend. The silyl end-capping groups differ from each other by theirfunctional groups. This method includes providing at least onesilanol-terminated polymer; at least two different silane end-cappingcomponents having different reaction affinities for silanol-terminatedpolymers; reacting the at least two different end-capping silanecomponents with at least one silanol-terminated polymer in the presenceof a catalytically effective amount of a catalyst. The silane componentsare selected in amounts sufficient to achieve hybrid end-capping, takinginto account the potential for non-hybrid by-products due to reactionkinetics and selectivity. The silanol-terminated backbone reactant maybe selected from silanol-terminated organopolysiloxanes (silicones),polyurethanes, polyamides, polyesters and copolymers and combinationsthereof.

[0009] Another aspect of the invention includes a method of preparing ahybrid end-capped silanol-terminated polymer backbone having differentreactive end-capping groups. This method includes providing asilanol-terminated polymer and at least two different silanes havingdifferent end-capping components and reacting said silanol-terminatedpolymer and said silanes, desirably in the presence of a catalyticallyeffective amount of a catalyst reagent, the amount of said end-cappingsilane components sufficient to achieve a desired end-capping ratio ofsaid first silane end-capping component to said additional end-cappingsilane component.

[0010] Another aspect of the invention includes a hybrid end-cappedsilyl-terminated polymer having at least two different end-capped groupsproduced by a process which includes the aforementioned method ofpreparation steps.

[0011] Another aspect of the present invention includes a reactivesilicone polymer which is the reaction product of two silanes, each ofwhich possess different end-capping groups, and a silanol-terminatedpolymer. The reaction product may be a mixture of reactive siliconepolymers, but includes, desirably in a predominant amount an alkoxysilyl-terminated end-capped reactive polymer corresponding to thestructure:

[0012] wherein A is a backbone portion selection from silanes,polyurethanes, polyesters and combinations thereof, n is 1-1,200; A isdesirably a polyorganosiloxane represented by the repeating structure:

[0013] wherein R¹ and R² may be identical or different monovalenthydrocarbon radicals C₁₋₁₀; desirably R¹ and R² are methyl groups; R³and R⁵ are different functional groups having up to 10 carbon atoms andare selected from (meth)acryl, amino (primary, secondary and tertiaryamines), vinyl, alkoxy, aryloxy, acetoxy, oxime and combinationsthereof; R³ or R⁵ may also be a monovalent heterohydrocarbon radicalhaving up to 10 carbon atoms (C₁₋₁₀), wherein the hetero atoms areselected from O, N and S; R⁴ is alkyl (C₁₋₁₀) and desirably methyl,ethyl or isopropyl; R⁴ may also be —CH₂CH₂OCH₃.

[0014] The present invention provides for various hybrid end-cappingcombinations. For example, one terminal silicon atom on the reactionproduct may have, directly or indirectly, alkoxy and aminofunctionality, while the other terminal silicon atom has, directly orindirectly, alkoxy and vinyl functionality. As another example, oneterminal silicon atom on the reaction product may have alkoxy and(meth)acryl functionality, while the other terminal silicon atom hasvinyl and alkoxy functionality. A particularly desirable reactivepolymer formed by the process of the invention is a reactive siliconepolymer having different end-capped groups which include a combinationof amino, vinyl and alkoxy terminal functional groups.

[0015] Another aspect of the invention includes a reaction productmixture which is a combination of a hybrid end-capped reactive siliconecombination with non-hybrid end-capped reactive silicone. Desirably, thehybrid end-capped silicone is present in a predominant amount ascompared to non-hybrid silicone reaction products, and more desirablythe hybrid is present in a predominant amount relative to the totalreaction product combination.

[0016] The present invention also provides a polymerizable polymercomposition comprising the reaction product of an alkoxysilyl-terminated hybrid end-capped reactive polymer corresponding to thestructure I above.

[0017] The reactive polymers of the present invention may be cured usingone or more curing mechanisms or conditions. For example, moisturecuring, actinic radiation such as uv or visible light, heat, anaerobiccure or combination of these mechanisms may be employed.

[0018] Another aspect of the invention includes a method of providing apolymer coating on a part which includes applying the reactive polymercompositions to a surface of the part and exposing it to one or morecure conditions sufficient to at least partially cure the polymercomposition.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0019] A. Hybrid Reactive Polymers

[0020] The present invention provides a method for preparing hybridend-capped polymers, and particularly hybrid end-cappedpolysorganosiloxanes prepared by a single end-capping reaction process.Specifically, the inventive method includes reacting two differentend-capping silane components and at least one silanol-terminatedpolymer to form a reaction product as described further herein. Thereaction desirably proceeds in the presence of a catalyst such asbutyl-lithium, although other less desirably catalysts such as titanatesor tin compounds may be employed.

[0021] As previously discussed, attempts to produce differentend-capping groups on a single polymer backbone, and particularlysilicone backbones, have not been successful, due to the inability tocontrol differences in reaction rates between various functionalizedend-capping silanes. It has now been discovered that if the reactionaffinities of the different end-capping silanes are properly accountedfor, the competitive reaction between silanes for available silanolreactant can be properly controlled to produce a hybrid end-cappedreaction product.

[0022] The present invention provides for hybrid end-capping byselecting amounts of each silane to obtain silyl-terminated polymers,and desirably alkoxy silyl-terminated polymers, having differentreactive end-capped groups. The silane or silanes having slower reactionrates are desirably provided in excess of the silane having a higherreaction rate. The relative amounts of each will vary depending on thesilanes chosen. Desirably, the ratio of one silane to another is about10:1 to about 1:10. In embodiments where three different silanes areadded, a desirable ratio is about 1:2:1. Use of more than three silanesare also contemplated.

[0023] The inventive “hybrid” reactive polymers may be utilized asintermediate products or in curable resin compositions which include acure system. Additionally, the inventive process provides an in situmethod of producing a hybrid end-capped reactive polymers, as opposed tothe manufacturing and storing of multiple reactive polymers for use insubsequent physical mixtures or solutions. Furthermore, the inventivepolymers are extremely stable without the further addition ofstabilizers, which enable them to be shipped as a final “hybrid” productthat is specifically tailored to a customer's needs. This alleviates theburden of the customer having to physically mix two different end-cappedpolyorganosiloxanes together to form a hybrid-like product.

[0024] The amounts of each silane necessary to obtain a predominantamount of hybrid reaction product can be determined in advance. Forexample, prior to reaction, the hydroxy content of thesilanol-terminated polymer component, e.g. silanol-terminatedpolyorganosiloxane, is determined by a suitable method. Based on thehydroxy content of the silanol-terminated component, the total amount ofsilanes, as well as the relative amounts of each, can be calculated toreach a predominant amount of the desired hybrid reaction product, orthe desired ratio of different end-capping groups on the final reactionproduct. Desirably, the reaction products of the present inventioncomprise about 35% or more, and more desirably about 60% or moresilyl-terminated polymers having different reactive end-capped groups.Other non-hybrid polymers having reactive end-groups may also bepresent. Desirably, care is taken in determining the relative amounts ofthe silane components, to account for differences in their reactionrates and ensure that no one silane is substantially unable to providethe desired end-capping. The total amount of the silane components aredesirably sufficient to substantially complete the end-capping reactionof the silanol-terminated polymer or polymers. Desirably, about 0.5moles to about 4.5 moles of the silane components are added for everymole of silanol-terminated polymer backbone component.

[0025] Subsequent to the initial hybrid end-capping, which usuallyvaries from about 2 to about 4 hours, additional end-capping silane isdesirably added to ensure that remaining silanol-terminated polymer issubstantially reacted. Regardless of the initial reaction time, thisstep desirably is performed at a time in the reaction such that chainextension is substantially alleviated.

[0026] The hybrid end-capped reactive polymer formed in accordance withthe invention desirably is an alkoxy silyl-terminated organopolysiloxanehaving, in addition to the alkoxy functionality, at least one additionalfunctional group on the end-capping portion, whereby these additionalfunctional groups are different for each terminal end. These differentfunctional groups are selected from alkoxy, amino, vinyl, aryloxy,acetoxy, oxime, (meth)acryl and combinations thereof on each end.

[0027] The resultant silyl-terminated organopolysiloxanes are stablematerials as measured by their ability to maintain substantiallyconstant viscosity values (cps) over time.

[0028] Aminopropyldimethoxy/vinyldimethoxy terminatedpolydimethylsiloxane polymers (hybrid DAM/VDM polymers) are examples ofparticularly desirable alkoxy silyl-terminated polymers of the presentinvention. This polymer is formed from reacting aminopropylalkoxysilane(DAM) and vinyl alkoxysilane (VDM) with a silanol-terminatedpolydimethylsiloxanes in a formulation ratio of 17.67% by weight DAM to82.33% by weight VDM, thereby producing a 1:1 molar ratio of the aminoto the vinyl functionality in the reaction product. The resultantreaction product is represented by a predominant amount of the reactivepolymer having the following structure:

[0029] Desirably, the alkoxy silyl-terminated polymers of the presentinvention are reactive organopolysiloxanes having vinyl and aminefunctionalities. Diverse end-cap functionality, in addition tocontributing to physical properties, allows for multiple curing systems.For instance, a hybrid polymer having end-capped groups containingalkoxy, (meth)acrylate and vinyl groups may be capable of curing bymoisture, photo and heat curing mechanisms. Alternatively, the reactivesilicones of the present invention may be fully cured using only one ofthese curing mechanisms.

[0030] B. Formation of the Hybrid Polymers

[0031] The reactive hybrid silicone polymers are made from thecondensation reaction of two different silanes, having differentreactive end-capping groups, with at least one silanol-terminatedpolyorganosiloxane.

[0032] The silane components of the present invention may be selectedfrom any silane which is capable of end-capping a polysiloxane. Thesilane is chosen based on the properties that it will impart to thefinal silicone end product.

[0033] The silane components have the general formula:

(R⁶)Si(OR⁷)₃   IV

[0034] wherein R⁶ and R⁷ can be identical or different monovalenthydrocarbon radicals having C₁₋₁₀;

[0035] R⁶ may also be a monovalent heterohydrocarbon radical having 1 to10 carbon atoms wherein the hetero atoms are selected from the groupconsisting of halo atoms, O, N and S.

[0036] Desirably, R⁶ and R⁷ are selected from the group consisting ofmethyl, ethyl, isopropyl, vinyl, phenyl, methacryloxypropyl andnorbornenyltrimethoxy; and R⁷ is desirably selected from the groupconsisting of methyl, ethyl, isopropyl and CH₂CH₂OCH₃. Of particularusefulness in the present invention are vinyltrimethoxy silane andaminopropyltrimethoxy silane. Tertiary and secondary aminoalkoxysilanesare also useful.

[0037] Other polyalkoxysilanes useful in the present invention include:

[0038] Si(OCH₃)₄, Si(OCH₂CH₃)₄, Si(OCH₂CH₂CH₃)₄, (CH₃O)₃SiCH₃,(CH₃O)₃SiCH═CH₂, (C₂H₅O)₃SiCH═CH₂, (CH₃O)₃SiCH₂—CH═CH₂,(CH₃O)₃Si[CH₂—(CH₃)C═CH₂], (C₂H₅O)₃Si(OCH₃), Si(OCH₂—CH₂—OCH₃)₄,CH₃Si(OCH₂—CH₂—OCH₃)₃, CH₂═CHSi(OCH₂CH₂OCH₃)₃, C₆H₅Si(OCH₃)₃,C₆H₅Si(OCH₂—CH₂—OCH₃)₃,

[0039] (CH₃O)₃Si[(CH₂)₃O—CH₂—CH CH₂], (CH₃O)₃Si[(CH₂)₃—Cl],(CH₃O)₃Si[(CH₂)₃OOC(CH₃)C═CH₂], (C₂H₅O)₃Si(CH₂)₂CH₂—Cl,(CH₃O)₃Si(CH₂)₃NH₂, (C₂H₅O)₃Si(CH₂)₃NH₂, (CH₃O)₃Si(CH₂)₃NH(CH₂)₂NH₂,(C₂H₅O)₃Si(CH₂)₃NH(CH₂)₂NH₂, (CH₃O)₃—Si(CH₂)₃SH,(CH₃O)₃Si[(CH₂)₃OOCH₂═CH], and

[0040] The aforementioned silane components are reacted with one or moresilanol-terminated polymer components, which can be virtually any usefulsilanol-terminated material. Useful polymer components include fromabout 50 cps silanol-terminated polydimethylsiloxane, to about 150,000cps silanol-terminated polydimethylsiloxane and combinations thereof Thesilanol-terminated polyorganosiloxane has the general formula:

HOSi-A-SiOH   V

[0041] wherein A represents a polymer or copolymer backbone, which canbe any number of combinations of polyurethane, silicone, polyamide,polyether and the like.

[0042] An example of one such silanol-terminated polymer backbone ispolydimethylsiloxane having the formula:

[0043] The number of repeating units will determine the molecular weightand hence the viscosity of this starting material. Thus, n can be, forexample, an integer which, for example, can be from about 1 to about1,200, desirably from about 10 to about 1,000. The viscosity of thesematerials is not critical and can easily be chosen to fit a particularproduct application, particularly because the alkoxy terminated endproduct of this reaction will have substantially the same viscosity asthe silanol-terminated reactant. Viscosities of these silanol-terminatedpolymer backbone can range from about 1 cps to about 150,000 cps(Brookfield, 25° C.). Desirably, the silanol-terminated polymer backboneused in the present invention is from about 50 to about 150,000 cps.

[0044] The reaction of the present invention utilizes a catalyticallyeffective amount of a catalyst. Desirable catalysts includeorgano-lithium reagents, which are represented by the formula LiR¹²wherein the organo group R¹² is selected from the group consisting ofC₁₋₁₈ alkyl, C₁₋₁₈ aryl, C₁₋₁₈ alkylaryl, C₁₋₁₈ arylalkyl, C-₁₁₈alkenyl, C-₁₋₁₈ alkynyl, amine-contain compounds, as well asorganosilicon-containing compounds. R¹² can have from 1 to 18 carbonatoms in the chain (C₁₋₁₈). These reagents provide enhanced processingand improved quality of product made therefrom.

[0045] The organo-lithium catalyst is preferably an alkyl lithium suchas methyl, n-butyl, sec-butyl, t-butyl, n-hexyl, 2-ethylhexyl butyl andn-octyl butyl lithium. A particularly desirable catalyst isN-butyllithium in hexane (1.6 Molar). Other useful catalysts includephenyl lithium, vinyl lithium, lithium phenylacetylide, lithium(trimethylsilyl) acetylide, lithium silanolates and lithiumsiloxanolates. The organo group can also be an amine-containingcompound, such as dimethylamide, diethylamide, diisopropylamide ordicyclohexylamide, or a silicon-containing compound.

[0046] Useful lithium silanolates have the formula LiOSiR⁹R¹⁰R¹¹ whereinR⁹ and R¹⁰ are monovalent hydrocarbon radicals C₁₋₁₀, desirably alkylsuch as methyl, ethyl and butyl, as well as aryl such as phenyl; and R¹¹is an alkyl or aryl group with C₁₋₁₈.

[0047] More particularly, useful lithium siloxanolates have the formulaLi(OSiR⁹R¹⁰O)_(t)SiR⁹R¹⁰R¹¹ wherein R⁹ and R¹⁰ are as described above;R¹¹ is as described above and t is an integer, desirably from 1 to 10.

[0048] The organo-lithium reagents are used in catalytically effectiveamounts. Generally, this amount will vary with the specific catalyst andreactant materials but about 1 to 1000 ppm based on the atomic weight oflithium are useful. A more preferred range is 15-250 ppm. Removal of theresidual organo-lithium catalyst is easily accomplished throughfiltration. This catalyst system does not generate offensive odors as doother catalysts.

[0049] Desirably, neither polar nor aprotic solvents are introduced tothe catalyst solution or the reaction mixture, thereby preventingundesired and uncontrolled catalyst regeneration and subsequent siloxanebond cleavage. However, insignificant amounts of alcohol are produced insitu during the reaction. The presence of this minor byproduct is sosmall that no perceptible drop or effect on the viscosity stability ofthe final product is observed. These minor amounts of alcohol byproductcan be optionally removed during or immediately subsequent to thereaction. It is desirable that no titanium catalyst is to be used in theformulation of the polymer, and therefore no residual titanium will beleft in the thus formed fluid. Absence of residual titanium minimizes“thick-phasing”. The organo-lithium catalyst, which is only effective inend-capping the organopolysiloxane but not effective in curing theend-capped product, is quenched to form a salt such as lithiumcarbonate, which is not reactive in the system and is easily removed.The resultant hybrid end-capped fluid is substantially free of catalystresidue and monoalkoxy functional end groups.

[0050] The method and compositions of the present invention can be mixedwith or include other conventional additives such as curing agents,viscosity modifiers, initiators, promoters, pigments, moisturescavengers and the like to form a one-part curable composition.Particularly useful viscosity modifiers include fumed silica, silanetreated, calcium carbonate, calcium carbonate (hydrophobic) andcombinations thereof Desirable pigments additives include carbon black.Moisture scavengers such as methyltrimethoxysilane andvinyltrimethyloxysilane are useful. Other particularly useful additivesinclude hexamethyldisilazane, vinyltrimethoxysilane,aminopropyltriethoxysilane, dioctyltindicarboxylate and combinationsthereof.

[0051] The present invention also includes a method of using a “hybrid”end-capped silyl-terminated reactive polymer composition which includeone or more curing agents. The method includes applying the reactivepolymer composition to an article and subsequently exposing thecomposition to cure conditions. Curing may result from moisture, actinicradiation such as uv light, heat, anaerobic cure and combinationsthereof.

[0052] Where photo curing is desirable, any known radical or cationicphotoinitiator can be used. Useful photoinitiators include benzoin andsubstituted benzoin compounds, benzophenone, Michler's ketonedialkoxybenzophenones, dialkoxyacetophenones, and the like.Photoinitiators made compatible with silicones by bindingphotoinitiating groups to organosiloxane polymer backbones may also beused.

[0053] The amount of photoinitiator used in the composition willtypically be in the range of between about 0.1% and 5% of thecomposition. Depending on the characteristics of the particularphotoinitiator, however, amounts outside of this range may be employedwithout departing from the invention so long as they perform thefunction of rapidly and efficiently initiating polymerization. Inparticular, higher percentages may be required if silicone boundphotoinitiators are used with high equivalent weight per photoinitiatinggroup.

[0054] It should also be understood that while the photoinitiator isused as a separate ingredient, the formulations used in the inventivemethod are intended to include formulations in which photoinitiatinggroups are included on the backbone of the same silanol-terminatedpolymer. Desirable photo curing groups which may be attached to theorganopolysiloxane include acrylate, methacrylate and glycidoxy groups.

[0055] The inventive compositions may also contain other additives solong as they do not interfere with the curing mechanisms. These includeadhesion promoters such as glycidoxypropyltrimethoxysilane,aminopropyltrimethoxysilane, methacryloxypropyltrimethoxy-silane,triallyl-S-tria-zine-2,3,6( 1H.3H.5H)-trioneaminoethylaminopropyltrimethoxysilane and others known to those skilledin the art. Fillers such as silica, microballoon glass and the like areuseful for their conventional purposes.

[0056] The invention may be further understood with reference to thefollowing non-limiting examples. Percent weights are per the totalcomposition unless otherwise specified. Viscosities are measured using aBrookfield viscometer with either a spindle #6 or #4 at 10 rpm, 25° C.,unless otherwise specified.

EXAMPLES

[0057] In order to achieve a predominant amount of vinyl and aminoend-capping on an alkoxy silyl-terminated reaction product, each of theinventive examples uses a significantly greater amount ofvinyltrimethoxsilane as compared to aminopropyltrimethoxysilane. Thisproportion overcomes the tendency for the amino silane to dominate thereaction and allows for formation of the hybrid reaction product.

[0058] Standard silicone analytical analysis was used to determine thereaction products and their relative amounts. Useful analyticaltechniques include ²⁹Si NMR, Fluorinated NMR and proton ²⁹NMR methods.

Example I

[0059] Composition A in Table I is an example of the components andtheir respective amounts used to form the alkoxy silyl-terminatedsilicones having different reactive end-capping groups. TABLE IComposition A COMPONENT % by weight POLYSILOXANE 50,000 cpssilanol-terminated PDMS* 81.241 3,500 cps silanol-terminated PDMS*17.392 END-CAPPING SILANES Vinyltrimethoxysilane (1^(st) addition) 0.213Aminopropyltrimethoxysilane 0.256 Vinyltrimethoxysilane (2^(nd)addition) 0.789 CATALYST N-butyllithium in hexane (1.6 M) 0.109

[0060] The reaction products formed from Composition A include apredominant amount (by weight) of vinyldimethoxy/aminopropyldimethoxyterminated polydimethyl siloxane, as well as lesser amounts of othernon-hybrid end-capped reactive silicones. The reaction process isdescribed in Examples II-V below. Among the reaction products arepolymers having the following structures and being formed in theapproximate amounts given:

[0061] All Below Represent a Total of About 10% Weight

[0062] The reaction product mixture formed from Composition A was usedto formulate curable silicone Composition B as shown below: CompositionB Component Weight % Composition A 47.5 Calcium carbonate filler 45.4Carbon Black 1.0 Modified Silicone Dioxide filler 2.0 Moisture Catalyst0.17 Silane adhesion promoter 1.18 Silane Moisture Scavenger 2.5

[0063] As a comparison to inventive Composition B, Composition C wasformulation using a physical mixture of two polyorganosiloxanes, onehaving vinyl and alkoxy functionality on its end-capped groups and theother having amino and alkoxy functionality on its end-capped groups.Composition C Component Weight % Aminopropyldimethox-terminated 9.01polydimethylsiloxane (28,000 mw) Vinyldimethoxy-terminated 38.44polydimethylsiloxane (60,000 mw) Carbon black 1.0 Modified SiliconeDioxide filler 2.2 Moisture Catalyst 0.15 Silane adhesion promoter 1.3Silane moisture scavenger 2.5

[0064] Inventive Composition B containing a reactive mixture of thepresent invention was tested for cure speed, skin-over time, hardness,tensile strength, elongation and shear adhesion. The results, shown inTable II below, also provide comparative tests for the physical mixtureof Composition C. TABLE II COMPARATIVE INVENTIVE TEST COMPOSITION CCOMPOSTION B Cure Speed 23 Minutes 12 Minutes (Skin-Over Time) Skin-OverTime after 72 50 minutes 25 minutes hrs. aging @ 82° C. MOISTURE CUREDSAMPLES, 7 DAYS @ 25° C./50% Relative Humidity Hardness, Shore A 45 37Tensile Strength (psi) 269 ± 9  300 ± 5  Elongaton, % 158 ± 11  247 ± 5 Shear Adhesion, psi 98 ± 8  108 ± 2  (0.02″ gap on aluminum substrate)

[0065] As is evident from Table II, the inventive hybrid compositionsexhibit significantly faster skin-over times before and after aging thanthe physical mixtures, as well as higher tensile, elongation and shearvalues.

Example II

[0066] Preparation of Hybrid Vinyldimethoxy/aminopropyldiethoxyTerminated Polydimethylsiloxane

[0067] In a 10-liter mixer equipped with mechanical stirrer,heating/cooling capability, bottom sparge and thermometer was chargedwith 6.05 kilograms of an α,ω-hydroxyl terminated polydimethylsiloxane(50,000 cps viscosity) and 1.85 kilograms of an α,ω-hydroxyl terminatedpolydimethylsiloxane (3,500 cps viscosity). The fluids were heated to50° C. and bottom sparged with nitrogen for 45 minutes to remove anydissolved carbon dioxide gas. Vinyltrimethoxysilane (15.0 g) and3-aminopropyltriethoxysilane (30.0 g) were then added to the mixer overa period of 10 minutes.

[0068] The n-butyllithium in hexane solution (1.6M; 7.2 g) was thenadded to the mixer. The mixture was maintained at 50° C. under anitrogen sparge monitoring the viscosity change over time. After apredetermined time when the mixture first shows sign of viscosityincrease (1 hr, 30 min), the second amount of vinyltrimethoxysilane(40.0 g) and 3-aminopropyltriethoxysilane (5.6 g) was added to the mixerand reacted for one and a half hours maintaining a temperature of about50° C. with nitrogen sparge. A small quantity of the mixture (5.0 g) wasthen withdrawn and was mixed with 0.1 g n-propyl titanate to determinethe completion of the end-capping reaction. Upon passing this test thereaction catalyst was then quenched using carbon dioxide gas and water(Dry ice). The mixture was further vacuum stripped for 1 hour at 75° C.to remove all the volatile components to give a predominant amount ofvinyldimethoxy/aminopropyl-diethoxy terminated polydimethylsiloxane.

Example III

[0069] Preparation of Hybrid Vinyldimethoxy/aminopropyldiethoxyTerminated Polydimethylsiloxane

[0070] In a 10-liter mixer equipped with mechanical stirrer,heating/cooling capability, bottom sparge and thermometer was chargedwith 6.05 kilograms of an α,ω-hydroxyl terminated polydimethylsiloxane(50,000 cps viscosity) and 1.86 kilograms of an α,ω-hydroxyl terminatedpolydimethylsiloxane (3,500 cps viscosity). The fluids were heated to50° C. and bottom sparged with nitrogen for 45 minutes to remove anydissolved carbon dioxide gas. Vinyltrimethoxysilane (15.0 g) and3-aminopropyltriethoxysilane (30.0 g) were then added to the mixer overa period of 10 minutes.

[0071] The n-butyllithium in hexane solution (1.6M; 7.2 g) was thenadded to the mixer. The mixture was maintained at 50° C. under anitrogen sparge monitoring the viscosity change over time. After adetermined time when the mixture first shows sign of viscosity increase(1 hr, 30 min), the second amount of vinyltrimethoxysilane (58.0 g) and3-aminopropyltriethoxysilane (5.6 g) was added to the mixer and reactedfor one and a half hours maintaining temperature of 50° C. and nitrogensparge. A small quantity of the mixture (5.0 g) was then withdrawn andwas mixed with 0.1 g n-propyl titanate to determine the completion ofthe end-capping reaction. Upon passing this test the reaction catalystwas then quenched using carbon dioxide gas and water (Dry ice). Themixture was further vacuum stripped for 1 hour at 75° C. to remove allthe volatile components to give a predominant amount ofvinyldimethoxy/aminopropyl-diethoxy terminated polydimethylsiloxane.

Example IV

[0072] Preparation of Hybrid Vinyldimethoxy/aminopropyldimethoxyTerminated Polydimethylsiloxane.

[0073] In a 10-liter mixer equipped with mechanical stirrer,heating/cooling capability, bottom sparge and thermometer was chargedwith 6.40 kilograms of an α,ω-hydroxyl terminated polydimethylsiloxane(50,000 cps viscosity) and 1.50 kilograms of an α,ω-hydroxyl terminatedpolydimethylsiloxane (3,500 cps viscosity). The fluids were heated to50° C. and bottom sparged with nitrogen for 45 minutes to remove anydissolved carbon dioxide gas. Vinyltrimethoxysilane (16.0 g) and3-aminopropyltrimethoxysilane (23.0 g) were then added to the mixer overa period of 10 minutes.

[0074] The n-butyllithium in hexane solution (1.6M; 7.2 g) was thenadded to the mixer. The mixture was maintained at 50° C. under anitrogen sparge monitoring the viscosity change over time. After adetermined time when the mixture first shows sign of viscosity increase(1 hr, 30 min), the second amount of vinyltrimethoxysilane (62.0 g) wasadded to the mixer and reacted for one and a half hours maintainingtemperature of 50° C. and nitrogen sparge. A small quantity of themixture (5.0 g) was then withdrawn and was mixed with 0.1 g n-propyltitanate to determine the completion of the end-capping reaction. Uponpassing this test the reaction catalyst was then quenched using carbondioxide gas and water (Dry ice). The mixture was further vacuum strippedfor 1 hour at 50° C. to remove all the volatile components to give apredominant amount of vinyldimethoxy/aminopropyldimethoxy terminatedpolydimethylsiloxane.

Example V

[0075] Preparation of Hybrid Vinyldimethoxy/aminopropyldimethoxyTerminated Polydimethylsiloxane.

[0076] In a 75-liter mixer equipped with mechanical stirrer,heating/cooling capability, bottom sparge and thermometer was chargedwith 56.74 kilograms of an α,ω-hydroxyl terminated polydimethylsiloxane(50,000 cps viscosity) and 12.15 kilograms of an α,ω-hydroxyl terminatedpolydimethylsiloxane (3,500 cps viscosity). The fluids were heated to50° C. and bottom sparged with nitrogen for 45 minutes to remove anydissolved carbon dioxide gas. Vinyltrimethoxysilane (149 g) and3-aminopropyltrimethoxysilane (179 g) were then added to the mixer overa period of 10 minutes.

[0077] The n-butyllithium in hexane solution (1.6M; 76 g) was then addedto the mixer. The mixture was maintained at 50° C. under a nitrogensparge monitoring the viscosity change over time. After one and a halfhours (1 hr, 30 min), the second amount of vinyltrimethoxysilane (551 g)was added to the mixer and reacted for one and a half hours. The mixturewas vacuum stripped at 50° C. for the last one hour of the reaction. Asmall quantity of the mixture (5.0 g) was then withdrawn and was mixedwith 0.1 g n-propyl titanate to determine the completion of theend-capping reaction. The reaction catalyst was then quenched usingcarbon dioxide gas and water to give a predominant amount thevinyldimethoxy/aminopropyldimethoxy terminated polydimethylsiloxane. Theproduct was cooled to below 30° C. and then the moisture scavengingsilane, hexamethyldisilazane (153 g), was added and mixed into thevinyldimethoxy/aminopropyldimethoxy terminated polydimethylsiloxane.

Example VI

[0078] Preparation of Hybrid Vinyldimethoxy/methlacryloxypropyldimethoxyTerminated Polydimethylsiloxane.

[0079] In a 5 liter 4-neck round bottom flask equipped with mechanicalstirrer, heating mantle, sparge tube and thermometer is charged with947.1 gram of an α,ω-hydroxyl terminated polydimethylsiloxane (3500 cpsviscosity) and 1484.9 grams of an α,ω-hydroxyl terminatedpolydimethylsiloxane (750 cps viscosity). The fluids are heated to 50°C. and bottom sparged with nitrogen for 45 minutes to remove anydissolved carbon dioxide gas. Vinyltrimethoxysilane (10.4 g) andmethlacryloxypropyltrimethoxysilane (40.5 g) are then added to the mixerover a period of 10 minutes. The n-butyllithium in hexane solution(1.6M; 1.125 g) is then added to the mixer. The mixture is maintained at50° C. under a nitrogen sparge monitoring the viscosity change overtime. After a determined time when the mixture first shows sign ofviscosity increase, the second amount of vinyltrimethoxysilane (1.6 g)and methlacryloxypropyltrimethoxysilane (12.15 g) is added to the mixerand reacted for one and a half hours maintaining temperature of 50° C.and nitrogen sparge. A small quantity of the mixture (5.0 g) is thenwithdrawn and was mixed with 0.1 g n-propyl titanate to determine thecompletion of the end-capping reaction. Upon passing this test thereaction catalyst was then quenched using carbon dioxide gas and water(Dry ice). The mixture is further vacuum stripped for 1 hour at 50° C.to remove all the volatile components to yield a predominant amount ofvinyldimethoxy/methlacryloxypropyldimethoxy terminatedpolydimethylsiloxane.

[0080] The invention being thus described, it will now be evident tothose skilled in the art that the same may be varied in many ways. Suchvariations are not to be regarded as a departure from the spirit andscope of the invention and all such modifications are intended to beincluded within the scope of the following claims.

Comparative Example A

[0081] This comparative example demonstrates that the failure to accountfor the differing reaction rates of the respective silanes, by theadjustment of their respective amounts during the end-capping reaction,does not result in a useful hybrid reaction product. This example uses asubstantially greater amount of vinyltrimethoxysilane than3-aminopropyltrimethoxysilane.

[0082] In a 10-liter mixer equipped with mechanical stirrer,heating/cooling capability, bottom sparge and thermometer was chargedwith 6.05 kilograms of an α,ω-hydroxyl terminated polydimethylsiloxane(50,000 cps viscosity) and 1.85 kilograms of an α,ω-hydroxyl terminatedpolydimethylsiloxane (3,500 cps viscosity). The fluids were heated to50° C. and bottom sparged with nitrogen for 45 minutes to remove anydissolved carbon dioxide gas. Vinyltrimethoxysilane (55.0 g) and3-aminopropyltriethoxysilane (35.0 g) were then added to the mixer overa period of 10 minutes.

[0083] The n-butyllithium in hexane solution (1.6M; 7.2 g) was thenadded to the mixer. The mixture was maintained at 50° C. under anitrogen sparge monitoring the viscosity change over time. Mixturerapidly rose in viscosity upon addition of n-butyllithium to over fourtimes the viscosity of the desired product after only 2 hours reaction.A small quantity of this mixture (5.0 g) was taken and was mixed with0.1 g n-propyl titanate to determine the completion of the end-cappingreaction. The sample rapidly gelled upon mixing indicating significanthydroxyl groups still present and that the polymer was not properlyend-capped. The batch continued to rise in viscosity to a level notuseable after only three hours.

Comparative Example B

[0084] This comparative example demonstrates that use of primary aminosilanes alone as end-cappers do not yield reaction products useful forformulating adhesive compositions due to their spurious reactions,resulting in viscosity increases, in air without a moisture catalyst.These results are in contrast to the relatively stable reaction productsobtained when the amino functionality is present on the hybrid siliconesof the present invention.

[0085] In a 2 liter 4-neck round bottom flask equipped with mechanicalstirrer, heating mantle, sparge tube and thermometer was charged with1000 g of an α,ω-hydroxyl terminated polydimethyl-siloxane (3500 cpsviscosity). The fluid was heated to 120° C. and stripped for 2 hours toremove any dissolved carbon dioxide gas and water. The mixture wascooled to room temperature and then the 3-aminopropyltrimethoxysilane(15.34 g) and n-butyllithium in hexane solution (1.6M, 0.9 ml) wasadded. The mixture was stirred while under vacuum for 1 hour to completethe reaction. The reaction catalyst was then quenched using carbondioxide and water (Dry Ice) and sample de-aired. The polymer wasself-reactive with air to cure overnight without a catalyst. Materialcould not be formulated into adhesive product since it cured duringformulating.

What is claimed:
 1. A method for preparing a silyl-terminated polymerterminated with different reactive end-capping groups comprising: a.)providing at least one silanol-terminated polymer and at least twoend-capping silane components having different end-capping groups; andb.) reacting said at least two end-capping silane components with saidat least one silanol-terminated polymer, said silane components beingpresent in amounts sufficient to form said alkoxy silyl-terminatedpolymer terminated with different reactive end-capped groups.
 2. Themethod of claim 1 wherein said silanes having different reactionaffinities for said silanol-terminated polymer.
 3. The method of claim 1wherein said reacting takes place in the pressure of a catalyticallyeffective amount of a catalyst.
 4. The method of claim 1, furthercomprising adding additional end-capping silane component tosubstantially end-cap remaining non-reacted silanol-terminated polymers.5. The method of claim 4, wherein said additional end-capping silanecomponent is different from said end-capping silane components of stepa.).
 6. The method of claim 4 wherein said additional end-capping silanecomponent is the silane having the a lesser reaction affinity forsilanol-terminated polymers than one of said silane components in stepa.).
 7. The method of claim 1, wherein said at least two end-cappingsilane components are aminopropyltrimethoxysilane andvinyltrimethoxysilane present in amounts sufficient to achieve areaction product comprising a reactive alkoxy silyl-terminated polymerhaving amino and vinyl end-capping groups.
 8. The method claim 1,wherein said reactive end-capping silane components include one or morefunctional groups selected from the group consisting of alkoxy, aryloxy,(meth)acryl, vinyl, amino, acetoxy, oxime and combinations thereof. 9.The method of claim 1, wherein said reactive polymer has a backboneselected from the group consisting of silicone, polyurethane, polyamide,polyester and combinations and copolymers thereof.
 10. The method ofclaim 1, wherein said end-capping silane components are selected fromthe group consisting of vinyltrimethoxysilane, vinyltriethoxysilane,butyl aminopropyl methoxysilane, aminopropyltrimethoxysilane,aminopropyltriethoxysilane, butylaminopropyldiethoxysilane andcombinations thereof.
 11. The method of claim 1 wherein the reactionproduct formed therefrom comprises at least 35% by weight of said alkoxysilyl-terminated polymer having different reactive end-capping groups.12. The method of claim 1, wherein said reactive end-capping groups areselected from moisture reactive groups, UV light reactive groups, heatreactive groups, anaerobically curable groups and combinations thereof.13. The method of claim 1, wherein said alkoxy silyl-terminated polymerhaving different reactive end-capping groups corresponds to thestructure:

wherein A represents a polymer or copolymer backbone selected from thegroup consisting of polyurethane, silicone, polyamide, polyether,polyester and combinations thereof, R³ and R⁵ are different functioninggroups having up to 10 carbon atoms and are selected from (meth)acryl,amino, vinyl, alkoxy, aryloxy, acetoxy, oxime and combinations thereof,and either R³ or R⁵ may also be a monovalent heterhydrocarbon radicalhaving up to 10 carbon atoms (C₁₋₁₀), wherein the hetero atoms areselected from O, N and S; R⁴ is alkyl (C₁₋₁₀) or —CH₂CH₂OCH₃.
 14. Themethod of claim 13 wherein A is an organopolysiloxane.
 15. The method ofclaim 1, wherein said at least one silanol-terminated polymer has aviscosity from about 50 cps to about 150,000 cps.
 16. The method ofclaim 1, wherein said end-capping silane components are added in amountsof about 0.5 moles to about 4.5 moles for every mole ofsilanol-terminated polymer component.
 17. The method of claim 3, whereinsaid catalyst reagent is an organolithium reagent represented by theformula: LiR¹⁴ wherein the organo group is selected from the groupconsisting of C1-18 alkyl, aryl, alkylaryl, arylalkyl, alkenyl, andalkynyl groups, an amine-containing compound and anorganosilicon-containing compound.
 18. The method of claim 17, whereinthe organo-lithium reagent is selected from the group consisting ofmethyl lithium, n-butyl lithium, sec-butyl lithium, t-butyl lithium,n-hexyl lithium, 2-ethylhexyl lithium and n-octyl lithium.
 19. Themethod according to claim 1, wherein said hybrid end-cappedsilyl-terminated polymer is an aminopropyldimethoxy/vinyldimethoxyend-capped polydimethylsiloxane polymer.
 20. The method of claim 1wherein the reaction product of step b.) comprises a combination ofend-capped polymers having a predominant amount of alkoxysilyl-terminated polymer having different reactive end-capping groups.21. An end-capped silyl polymer having different reactive end-cappedgroups comprising: a. providing at least one silanol-terminated polymerand at least two end-capping silane components having different reactiveend-capping groups; b. reacting said at least two end-capped silanecomponents with said silanol-terminated polymer, said silane componentsbeing present in an amount sufficient to produce at least a predominantamount relative to other reaction products of an end-cappedsilyl-terminated polymer having different reactive end-capping groups;and c. end-capping remaining non-reacted silanol-terminated polymerbackbone by adding excess of said first silane component.
 22. Thepolymer of claim 21 wherein said predominant amount is about 35% byweight or greater.
 23. The method of claim 21, wherein said predominantamount is based on the total amount of other reaction products.
 24. Analkoxy silyl-terminated polymer having different reactive end-cappedgroups corresponding to the structure:

wherein A represents a polymer or copolymer backbone selected from thegroup consisting of polyurethane, silicone, polyamide, polyether,polyester and combinations thereof; R³ and R⁵ are different functionalgroups having up to 10 carbon atoms and are selected from (meth)acryl,amino, vinyl, alkoxy, aryloxy, acetoxy, oxime and combinations thereof,and either R³ or R⁵ may also be a monovalent heterohydrocarbon radicalhaving up to 10 carbon atoms (C₁₋₁₀), wherein the hetero atoms areselected from O, N and S; R⁴ is alkyl (C₁₋₁₀) or —CH₂CH₂OCH₃.
 25. Thealkoxy silyl-terminated polymer of claim 24 comprisingaminopropyldimethoxy/vinyldimethoxy terminated polydimethylsiloxane. 26.A polymerizable polymer composition comprising the reaction product of:a.) an alkoxy silyl-terminated polymer corresponding to the structure:

wherein A represents a polymer or copolymer backbone selected from thegroup consisting of polyurethane, silicone, polyamide, polyether,polyester and combinations thereof R³ and R⁵ are different functionalgroups having up to 10 carbon atoms and are selected from (meth)acryl,amino, vinyl, alkoxy, aryloxy, acetoxy, oxime and combinations thereof,R³ or R⁵ may be a monovalent heterhydrocarbon radical having up to 10carbon atoms (C₁₋₁₀), wherein the hetero atoms are selected from O, Nand S, and R⁴ is alkyl (C₁₋₁₀) or —CH₂CH₂OCH₃; and b.) a curinglyeffective amount of curing catalyst.
 27. The composition of claim 26wherein said alkoxy silyl-terminated polymer includes alkoxy, amino andvinyl end-capping functionality.
 28. The composition of claim 26,wherein said composition includes one or more catalysts selected frommoisture curing catalysts, actinic radiation catalysts, heat curingcatalysts, anaerobic curing catalysts and combinations thereof.
 29. Thecomposition of claim 28, wherein said moisture catalysts are selectedfrom the group consisting of titinate catalysts, tin catalysts, andcombinations thereof.
 30. The composition of claim 28, wherein saidactinic radiation catalysts are selected from the group consisting ofbenzoin, benzophenones, acetophenones and combinations thereof.
 31. Thecomposition of claim 28, wherein said heat curing catalysts are selectedfrom the group consisting of platinum catalysts, rhodium catalysts,ruthenium, irridium and combinations thereof.
 32. The composition ofclaim 28, wherein said cationic initiators are ionium salts.
 33. Amethod of providing a polymeric coating on a part comprising: (1)applying to said part a reactive silicone composition comprising apredominant amount by weight of any single component an alkoxysilyl-terminated polyorginosiloxane having different reactive end-cappedgroups, and (2) exposing said composition to one or more cure conditionsselected from moisture, actinic radiation and heat for a sufficient timeto at least partially cure said polymeric coating.
 34. The method ofclaim 30, wherein said curing agent is selected from the groupconsisting of moisture curing agents, actinic radiation curing agents,heat curing agents, anaerobic curing agents and combinations thereof.35. The method of claim 30, wherein said reactive silicone compositioncomprises an aminopropyldimethoxy/vinyldimethoxy end-capped terminatedpolydimethylsiloxane polymer.